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gpgpu_gles3.c
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gpgpu_gles3.c
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// clang -Os gpgpu_gles3.c -o gpgpu_gles3 -lglfw -lGL
#include <stdio.h>
#include <stdlib.h>
#define DEBUG
#include "gpgpu_gles3.h"
const char *shader_out[] = { "res" };
const char* shader_source = "#version 320 es\n" STRINGIFY(
out vec4 res;
uniform highp samplerBuffer X;
void main() {
res = vec4(gl_VertexID);
//res = texelFetch(X, gl_VertexID);
}
);
void compute()
{
uint32_t num = 100;
float data[num];
for (int i=0; i<num; i++) {
data[i] = i;
}
GLuint program = gpu_compile(shader_source, shader_out);
GLuint vao = 0;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
GLuint vbo[2];
glGenBuffers(2, vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
glBufferData(GL_ARRAY_BUFFER, sizeof(data), /*&data[0]*/0, GL_STREAM_DRAW);
GPU_CHECK();
// create texture buffer object
glBindBuffer(GL_TEXTURE_BUFFER, vbo[0]);
glBufferData(GL_TEXTURE_BUFFER, num*sizeof(float), data, GL_STATIC_DRAW);
glBindTexture(GL_TEXTURE_BUFFER, vbo[0]);
glTexBuffer(GL_TEXTURE_BUFFER, GL_RGBA32F, vbo[0]);
GPU_CHECK();
// create a transform feedback object
GLuint fb = 0;
glGenTransformFeedbacks(1, &fb);
glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, fb);
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, vbo[1]);
// glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, 0);
GPU_CHECK();
/* printf("X:%d\n", glGetUniformLocation(program, "X"));
// glUseProgram(program);
glUniform1ui(glGetUniformLocation(program, "X"), vbo[0]);
GPU_CHECK();*/
glEnable(GL_RASTERIZER_DISCARD);
// glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, fb);
glBeginTransformFeedback(GL_POINTS);
glDrawArrays(GL_POINTS, 0, num);
glEndTransformFeedback();
// glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, 0);
glDisable(GL_RASTERIZER_DISCARD);
// glUseProgram(0);
GPU_CHECK();
// swap
/* glBindTexture(GL_TEXTURE_BUFFER, 0);
glBindBuffer(GL_TEXTURE_BUFFER, 0);
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, 0);
glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, vbo[0]);
glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, 0);
GPU_CHECK();
glUniform1ui(glGetUniformLocation(program, "X"), vbo[1]);
glEnable(GL_RASTERIZER_DISCARD);
glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, fb);
glBeginTransformFeedback(GL_POINTS);
glDrawArrays(GL_POINTS, 0, num);
glEndTransformFeedback();
glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, 0);
glDisable(GL_RASTERIZER_DISCARD);*/
GLfloat *feedback;
glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
feedback = glMapBufferRange(GL_ARRAY_BUFFER, 0, num*sizeof(float), GL_MAP_READ_BIT);
printf("glMapBufferRange: ");
for (int i=0; i<num; i++) {
printf("%f ", feedback[i]);
}
printf("\n");
glUnmapBuffer(GL_ARRAY_BUFFER);
GPU_CHECK();
printf("glGetBufferSubData: ");
glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);
glGetBufferSubData(GL_ARRAY_BUFFER, 0, num*sizeof(float), data);
GPU_CHECK();
for (int i=0; i<num; i++) {
printf("%f ", data[i]);
}
printf("\n");
glDeleteTransformFeedbacks(1, &fb);
glDeleteBuffers(2, vbo);
glDeleteVertexArrays(1, &vao);
glDeleteProgram(program);
}
int main(int argc, char* argv[])
{
gpu_init();
compute();
gpu_term();
}